Corrosion inhibition



corrosion of metals in contact with acids.

3,077,453 Patented Feb. 12, 1963 lice The present invention relates tothe prevention of corrosion of metals in contact with acids. Moreparticularly the present invention relates to corrosion inhibiting Icompositions containing acetylenic or nitrogen compounds and tincompounds.

Many compounds have been proposed to inhibit the These compounds andcompositions containing these compounds have proved satisfactory inlimited application. However, to date, no single composition has beenfound which is effective in preventing corrosion of metal in contactwith all of the industrial acids in use today. Further, many of theinhibitors, excellent at low temperatures, are ineifective attemperatures above about 80 C.

It is therefore an object of the present invention to provide a new anduseful composition for the prevention of corrosion of metals in contactwith acids. It is a further object of the present invention to provide acorrosion inhibitor composition which will be effective at temperaturesas high as 150 C., and further, which composition is effective over alonger period than heretofore thought possible. These and other objectswill become apparent to those skilled in the art from the followingdescription and claims.

It has now been found that the presence of the stannous ion inconjunction with the acetylenic or amine moiety of an organic compoundeffectively inhibits the corrosion of metal when such metal is incontact with aqueous acids. Thus, one can employ astannous-ion-producing compound in combination with an acetyleniccompound or in combination with an amine or both and obtain, when theinhibitor composition is mixed with an aqueous acid, a markedimprovement in corrosion inhibition over that obtained employing any oneof the ingredients alone or a combination of the ingredients withoutstannous ion. Good results have been obtained when the inhibitor com.-position contains stannous ion in the amounts of from as little as 2percent by weight to about 60 percent by weight. The amount of stannousion which in an aqueous acid composition imparts an improved eifect isfrom about 0.008 percent by weight to about 0.32 percent by weight, andpreferably from about 0.08 percent by weight to about 0.24 percent byweight based on the weight of the aqueous acid solution.

The stannous ion is conveniently incorporated in the inhibitorcomposition by employing such compounds, as for example, stannouschloride, stannous bromide, stannous sulfide, stannous oxide, theirhydrates and the like.

The acetylenic compounds which are synergized by the presence of thestannous ion are the acetylenic alcohols and diols, such as for example,propargyl alcohol, methylbutynol, butynediol, l-ethynylcyclohexanol, 3-methyl-l-nonyn-3-ol, 2-methyl-3-butyn-2-ol, and (AC-ethynyl2,4,6-trimethylbenzyl alcohol. Thus, in general, acetylenic compoundshaving the general formula wherein each R represents an independentlyselected radical of the group consisting of hydrogen, lower alkyl, i.e.,1 to 4 carbon'atoms, phenyl, substituted phenyl; or hydroxy loweralkyland the u-Rs may be fused together to form a 5 or 6 membered ring.

The amines which are effectively synergized by the ac.- tion of stannousion, either alone or in combination with the acetylenic compound, arefor example the mono, di and trialkyl amines having from 2 to 6 carbonatoms in each alkyl moiety as well as the 6 membered N-heterocyclicamines, i.e., the alkylpyridines and mixtures there of. Such aminesinclude ethylamine, diethylamine, triethyiamine, propylamine,dipropylamine, tripropylamine, mono, di and tributylamine, mono, di andtripentylamin'e, mono, di and trihexylamine, as well as their isomerssuch as isopropylamine, tertiary-butylamine and the like, and thealkylpyridines having from 1 to 5 nuclear alkyl substituents perpyridine, moiety, said alkyl substituents having from 1 to 12 carbonatoms, and preferably those having an average of 6 carbon atoms perpyridine moiety, such as a mixture of high-boilingtertiary-nitrogen-heterocyclic compounds having an equivalent weight ofapproximately (Alkylpyridine HR, a product of Union Carbide and Carbon(3.0.).v I

The following examples are illustrative of the present invention but arenot to be construed as limiting.

Examples 1-24 Concen- Concentration of Acetylenic or Alkyl tration Ex.pyridines in Inhibitor (percent by Stannous Metal Temp.. Corrosion RateNo. volume) Ion (per F.) .(lbsJitJ/day).

cent by weight) 1 none 0.32 API N80 Reaction rate same as for raw (unimhibited) acid. (1 0.32 175 D0.

.4 n 0 175 0.64. 4 MB 0. 32 175 0.30. .4 propargyl alcohol (Coded PA 0200 l.0. .4 PA 0. 32 200 0.19, .4 butynediol (Coded BD)- 0 175 0.56. .4DD 0. 32 175 0.025. 4 ethyriycyclohexanol (Coded ECH) 0 175 1 .0. ,4 ECH 0.32 175 0.21. .8 1:9 rrixture of MB and alkyipyri- 0 175 0.15.

dines HB (Coded KB), I 0.8 above mixture 0. 32 175 0.0 9. 0.4 1:1mixture of PA and H 0 200 0.40- ..do 0.32 200 0.025, 0.4 1:1 mixture ofBD and HB 0 175 0.013.

See footnote at end of table.

Concen- Concentration of Aeetylenlo or Alkyltration Er. pyridines inInhibitor (percent by Stamens Metal Temp., Corrosion Rate No. volume)Ion 1 (per- F.) (lbs/ttfi/day) cent by weight) 16 do 0.32 175 0.000.17"--- 0.6 1:1 mixture of PA and HB 250 0.40. 18 -.do 0.16 25 0,043;

1 Stannous ion was added as stannous chloride, SNClzJHzO. 2 Length oftest was 4 hours. 3 Length of test was 6 hours.

Examples 25-28 Other tests were run to determine the effect of various2O cmmmzmtion CPmentra" Corrosion Ex. Inhibitor tron Stan- Temp. astannous compounds to supply the stannous 1011 in the No. Metal (percentby nous Ion F.) (lbs/rm synergistic inhibitor mixtures. V01ume) ig gggbday) Acid 150 ml. hydrochloric acid Temperature 175 F. 3 Cast r n.0.41:1 mixture 150 0172 Length of test. 16 hours 150 M87 Metal A151 1010coupons (2.75" x 1.0" x 0.12") 175 0.0078 175 0.0066

Concentration Corrosion 1 PA-Propargy1 alcohol; HB-Alkylpyridines EB.Ex. Acetylenic Com- Concentration Stannous Rate No. pound (percent(percent by weight) (lbs/ftfl/ by volum day) Examples 41 to 52 2s 0.4methyl bu-- 0. 64 The efiect of the inhibitor system of the instantinven- Qao tron was determined in acids other than hydrochloric 8%? acidemploying propargyl alcohol; propargyl alcohol and stannous ion; and,propargyl alcohol, Alkylpyridines HB It is to be observed that thestannic ion does not impart any visible effect on the corrosion rate.

Examples 29-36 Corrosion rate determinations were made to determine theconcentration of stannous ion required, and the effect of thevariousconcentrations of stannous ion in the inhibitor mixture. In each testthe acid contained 0.4 percent by volume of a 1:1 mixture, by volume, ofpropargyl alcohol and Alkylpyridines HB (a product of Union Carbide andCarbon (10.).

1 Added as SnC1z.2HzO.

Examples 37 10 40 Corrosion tests were made to determine theeffectiveness of the inhibitor systems on metals commonly encountered inboth oil well treating and industrial cleaning operations. 1 w

Acid 1'50 n51. 5% hydrochloric acid Length of test 6 hours and stannousion containing inhibitor compositions.

Metal AISI 1010 coupons (2.75 x 1.0 X 0.12")

Concentration Ex. Acid Media, Stannous Corrosion No. AqueousConcentration Inhibitor Ion 1 Rate,

(perent (percent by volume) (percent (lbs/[L l by volume) by day)weight) 41..-. 5112804 0.4 PA 0 0.91 42.". 5 HQSOJ 0.4 PA 0 16 0.004743.... 5152504 0A 1:1 mixture of PA 0 0.15

and HE. 5 d0 0 16 0.0004 5 0.4 PA 0 0.14 5 04 PA 0. 16 0. 0055 5 0.41:1mixture of PA 0 0.14

and do 0 16 0.0009 0.4 PA" 0 0.10

0.1 PA 0.16 0. 0004 51.--- 5OH3COOH 0.4 1:1 mixture of PA 0 0.067 andHB.

' 1 'Added as SnCl2.2H2O.

Examples 53 to 63 Corrosion tests were made to determine the eifect ofother amines in the inhibitor compositions of the present invention. Thetests were the same as set forth in Examples 1 through'Z4 and theresults are set forth below:

Acid ...150 ml. aqueous 15% hydrochloric acid Length of test 16 hoursTemperature .1 C.

75 Metal "A151 1010 coupons EFFECT OF THE ADDITION OF STANNOUS ION TOVARIOUS AMINE AND AMINE-PROPARGYL ALCOHOL MIXTURES Concentra-Concentration tion Corrosion Ex. Concentration Amine Propargyl StamensRate No. (percent by volume) Alcohol Ion 1 (per- (lbs/ttfi/ (percent bycent by ay) volume) weight) 53 0.4 ethanolamine 1. 54 o 0. 96 55 0.2ethanolarnine 1. 0 56 do 0.83 57 0.4 cyclobexylamino 1. 0 58 0.2cyclohe. ;ylamine 1. 0 59 o 0. 89 60 0.4 1,2-propanedian1ine 1.0 m (in0. 57 62 0.2 l,2-propanedinmine. 1. 0 63 "do 0. 79

1 Stannous ion was added as stamens chloride, 81101221120.

This application is a continuation-in-part of application Serial No.736,707, filed May 21, 1958, now abandoned.

Iclaim:

1. A corrosion inhibitor composition consisting essentially of from 0 to98 parts by weight of an acetylenic alcohol having the formula R R0E0-(:0H

wherein each R represents a member selected from the group consisting ofhydrogen, lower alkyl, phenyl, cycloalkyl and hydroxyalkyl and whereinthe a-Rs may be joined together to form a ring, fro-m 2 to 60 parts byweight of a compound capable of providing a stannous ion, and from 98 to0 parts by weight of an amine per 100 parts of inhibitor composition,said amine being selected from the group consisting of alkylamines,dialkylamines and trialkylarnines having from 2 to 6 carbon atoms ineach alkyl moiety and alkyl pyridines having from 1 to 5 alkylsubstituents and from 1 to 12 carbon atoms in each substituent.

2. The corrosion inhibitor composition as set forth in claim 1 whereinsaid acetylenic compound is employed in from to 98 parts by weight andsaid stannous compound is employed in from to 2 parts by weightrespectively.

3. The corrision inhibitor composition as set forth in claim 1 whereinsaid stannous compound is employed in from 40 to 2 parts by weight andsaid amine is employed in from 60 to 98 parts by weight.

4. A composition consisting essentially of an aqueous acid and from0.008 to 0.32 part by weight of a corrosion inhibitor composition as setforth in claim 1 per parts of aqueous acid.

References Cited in the file of this patent UNITED STATES PATENTS1,678,776 Gravel et al. July 31, 1928 2,053,024 Dreyfus Sept. 1, 19362,097,847 Strauch Nov. 2, 1937 2,472,400 Bond et al June 7, 19492,806,067 Monroe et al. Sept. 10, 1957 2,814,593 Beiswanger et a1. Nov.26, 1957 2,846,294 Patterson et al Aug. 5, 1958 2,913,408 Pumpelly eta1. Nov. 19, 1959 2,955,083 Levin Oct. 4, 1960 FOREIGN PATENTS 235,291Switzerland Apr. 3, 1945

1. A CORROSION INHIBITOR COMPOSITION CONSISTING ESSENTIALLY OF FROM 0 TO98 PARTS BY EIGHT OF AN ACETYLENIC ALCOHOL HAVING THE FORMULA